Electricity was temporarily cut across several parts of the island on Vesak poya day, including Colombo, after an “unexpected system imbalance” forced controllers to disconnect supply to stabilise the grid, Energy Minister Anura Karunathilaka said Saturday.
The disruption struck shortly after midday on May 30, with the minister stating that authorities were working to restore electricity to affected areas “as quickly as possible.” Supply had been “temporarily disconnected as a measure to balance and stabilise the system,” he said, adding that restoration work was underway.
The trip followed an earlier voluntary appeal by the National System Operator (Private) Limited — the post-restructuring grid manager that succeeded the Ceylon Electricity Board’s control function — for rooftop solar panel owners to switch off their systems until 3:00 p.m. on Saturday. Newswire reported the NSO request was issued around midday and cited “a significant drop in electricity demand across the system” during the Vesak holiday window that required “careful management of power generation and supply to ensure stable grid operations.”
Vesak, the most important Buddhist festival of the year, sees factories, offices and schools close as families attend temple observances and dansal (free food stalls), causing a sharp midday demand slump while rooftop solar continues to generate at peak under clear skies. The same imbalance forced the regulator to issue a similar voluntary switch-off request on Avurudu day in April and an earlier mandatory shutdown of large rooftop solar systems between April 10 and 20. Distributed solar capacity has expanded rapidly under net-metering schemes, but baseload thermal and hydro plants have limited flexibility to ramp down quickly when generation exceeds demand.
By mid-afternoon, NSO said power had been restored to approximately 100 areas including Colombo. The operator confirmed the disconnection had been “necessitated by a system imbalance resulting from a significant drop in electricity demand, attributed to the Vesak Poya holiday and the long weekend.” With Sunday expected to repeat the holiday demand pattern, NSO has asked rooftop solar owners to voluntarily switch off their systems again from 8:00 a.m. to 3:00 p.m. on May 31.
The government has been pushing structural fixes, approving a 300 MW battery storage rollout for end-2026 and procuring grid stabilisation software to manage the surge in variable renewables. Until those come online, public holidays remain the most fragile windows for grid stability.
Sources: Ada Derana (initial trip) · Ada Derana (restoration) · Ada Derana (May 31 extension) · Newswire.
